Converge supported Python onto 3.8
Python 3.8 was specified in pyproject.toml (which is used by ruff when checking code), but some references still said 3.7.
Given that 3.7 is EOL, converge all references onto 3.8.
Python 3.8 was specified in pyproject.toml (which is used by ruff when checking code), but some references still said 3.7.
Given that 3.7 is EOL, converge all references onto 3.8.